Method of making two-piece valves



Ocf. 26 1926. 1,604,208

w. H; WASHBU'RNE Filed April 13, 1925 J LQ I fty i T a Patented Oct. 26, 1926.

UNITED STATES WILLIAM H. WASHBURNE, OF CHICAGO, ILIl LINOIS.

METHOD OF MAKING TWO-PIECE VALVES.

Application filed April 13, 1923. Serial No. 631,862.

In my prior applications bearing respec' ess and insure the realization to a maximum degree of the original purpose thereof.

The essence of the original process is the forging of a heated washer-like head on the ,end of a finished stem and the subsequent cooling of the work in such a manner that no further machining operation than the mere grinding of the valve face is necessary If the end of the stem is allowed to project slightly above the top of the head and a smooth top surface is desired the projecting portion of the stem must be ground off; this operation adding a little to the cost of the valve but being objectionable mainly because it causes a break in the continuity of the skin produced by the forging step. One of the objects of the present invention is to insure that the top end of the stem of each valve shall lie flush with or occupy some, otherdefinite relation 'to the top surface of the head.

In carrying out my process, as it had been developed" prior to the' present invention, it sometimes happened that the valve heads were tempered too hard or ever cracked or became distorted when the valves were suddenly dropped into a quenching bath upon removal from the forging dies. Sometimes, also, it was found that the heads were loose on the stems after the quenching step, this evidently being occasioned by the fact that the heads .were suddenly cooled from a temperature in the vicinity of the point of recalescence. Some metals, at least, in cooling, contract progressively as the recalescence point is approached and then, instead of continuing to contract, actually expand for a time as the cooling continues. It therefore sometimes happens that the conditions best adapted for the forging operation left the head at a temperature in the vicinity of the recalescence point at the moment it was dropped into the quenching bath and caused the head to he suddenly cooled at a time it was actually expanding, Another object of my invention is to make it possible to effect the cooling of the valves as they leave the forging dies in such a manner as to avoid the faults sometimes brought about by sudden quenching of the heads while at a high temperature.

I have found that it is possible to forge castv iron blanks into valve heads in accordance with my process and thus produce valves having steel stems and heads forged out of' cast iron. However, in forging the cast iron, the forging, stresses being in the nature of squeezing stresses and not hammer blows, a change in the texture of the metal takes place somewhat as it does in the puddling furnace and the apparatus which squeezes the free nonmetallic matter out of the plastic puddled iron; and the resulting valves are therefore different from valves consisting of stems having heads cast on the same. It may therefore be said that I have invented or discovered a new kind of a valve having a steel stem and a forged head made out of cast iron changed in character by the forging operation.

The various features of novelty whereby my invention is characterized will hereinafter he pointed out with particularity in the claims; but for a full understanding of my invention and of its objects and advantages, reference may be had to the following detailed description taken in connection with the accompanying drawing, wherein:

Figure 1 is a vertical section through a pair of forming dies ready to close upon a valvehead blank to forge it into the shape of a valve head and secure it to a stem in accordance with the present invention; Figs. 2, 3 and 4 are views similar to Fig. l, the lower portion of the lower die being broken away, showing successive stages in the forging operation; and Fig. 5 is a section through a modified form of blank which may conveniently be used when the head is to be made of cast iron.

The forging press may conveniently be substantially the same as in my aforesaid application Serial No. 538,548, there being two forming dies, a lower die 1, and an upper die 2; the lower die having a die cavity 3 so shaped that when the upper die member has moved into the cavity to the lowermost limit of its movement, that portion of the die cavthe same. The length of the stem-receiving forced down.

hole is such that when a stem is dropped into the same the upper grooved end 6 of the stem will lie within the mold cavity. The valve stem should be completely finished before it is placed in the die, in order to secure all of.

the advantages of the present invention.

The blank for the'head may be simply a thick washer 7 of approximately the diameter of the finished head.

The valve stem when placed in the die is cold, being conveniently at room temperature. The blank for the head is highly heat ed, preferably almost to a welding temperature. After the stem has been placed in the lower die the blank-is dropped into the mold cavity, as illustrated in Fig. 1, the grooved upper end of the stem lying within the hole in the blank. The upper die member is then The first action of the dies closing on the blank is illustrated in Fig. 2; the blank taking substantially the shape of the completed head and there remaining only comparatively small spaces in the mold cavity, mainly the grooves in the stem, to be filled. During the next stage of the process the die descends into the position shown in Fig. 3, in which the mold cavity is com pletely filled with the metal of the blank and this metal has also been brought into intimate contact with the bottoms of the grooves in the stem. The process may be stopped at this point or it may be carried farther to bring about the condition illustrated in Fig. 4.

If the downward movement of the upper die member be continued after the position illustrated in Fig. 3 is reached, there being no furtherv spaces left to fill, such movement must be accompanied by a compression of the metal in the mold cavity. When the pressure becomes sufiiciently great a neck or waist,will be formed in the grooved portion of the stem so that the stem will be larger in diameter near the'top and bottom faces of the valve than midway between these faces. The whole operation is performed so quickly that the stem does not have time to become heated and therefore the formation of the waist or neck is the result of acold drawing process imposed onthe stem.

In view of the fact that the metal in the stem must flow in the direction of the length;

of the stem duri n'g the formation of the neck o'r'waist, it preferable to. have the stem rest at its lower end upon a yieldingsupport so that the stem may yield in the downward direction during the drawingoperation. In the arrangement shown, the lower end of the stem rests on a block 9 which in turn rests on a coiled spring 10 supported by an adjustable plug 11 screw threaded into the bottom of the lower die member. The members 9 and 11 are preferably provided with axial openings 12 and 13 through which a knockout rod may be inserted to eject the valve at the end of the forging process.

The upper die member is preferably provided in its bottom face with a central recess 14 somewhat larger in diameter than the d ameter of the stem, so that the stem may rise above the top of the head without engaging with the upper die. In order to insure that the upper end of the stem Wlll not project beyond the top of the head in the finished valve, there may be placed in the recess 14 a plunger 15, behind which is a spring 16 stronger than the spring 10;,the lower end of the plunger being. flush with the under face of the upper die member and being smaller in diameter than the stem. The stem may therefore expand both upwardly and downwardly and cannot become distorted because of lack of capacity to do so during the final step in forming the neck or waist therein.

, An important factor in securing perfect results is the cooling of the valve as soon as it is completed. It is a well known fact that the expansion -and contraction of a metal upon heating and cooling is not at a constant radio per degree of temperature rise or fall, but is greatest between the approximate limits of 60 degrees F. and 700 degress F. If the valve is hot, say about 1450 degrees F., and the stem is cold, say about 60 degrees F., at the instant the swaging pressure is applied, it is evident that if the valve is removed from the die and permitted to cool to normal temperature slowly, there will be a transference of heat from the head to the stem until both are at an approximately uniform temperature of say about 600 degrees F. In thus becoming heated, the stem will have expanded considerably, so that after the temperature between the stem and the head has been equalized, the head and the stem will cool and shrink at the same rate. In other words, the full effect of the shrinkage of the head will not be utilized in the grip which the head has on the stem. However, if the head can be cooled before the stem becomes hot, the shrinking of the head will take place without a corresponding shrinking of the stem. There is another factor to be considered, and that is, that some metals, at least, at a definite point, known as the dilatation point, in cooling from a hi h temperature, expand for a time instea of continuing to contract. If a valve head he abruptly cooled by is still at a red heat and the stem is still cool enough to permit it to be taken up in the bare hands, and the stem is immersed in a bath of running water,-whi'ch carries away the heat as rapidly'as itis delivered to the stem by the head. After the head has become sufliciently cool, the valve is immersed in a suitable bath, which quickly cools the head and at the same time tempers it. This method of cooling not only insures a rigid connection between each head and its stem, but it also prevents cracking or distortion of the valves and the hardening to too great a degree, as sometimes happens when valves are suddenly cooled by quenching immediately upon removal from the dies.

As heretofore stated, the blanks for the valve heads may be of any desired metal, even of cast iron. Where "cast iron is used, the blanks. may initially be cast in shapes more nearly approaching those of completed heads than do blanks that are simply punched out of fiat plates. The heavy pressure to which the cast iron is subjected in the forging process seems to produce somewhat the same results as the puddling and squeezing process which changes cast iron into wrought iron, for the characteristics of the metal in the completed valve head are quite different from those of the original cast iron.

I claim:

1. The method of making a two-part valve which consists in inserting a stem into a hole of larger diameter extending through a heated valve-head blank; then forging the blank, in dies, while supporting the stem so that it may expand lengthwise, in either direction, to cause the metal to flow into intimate contact with the stem and simultaneously give to the blank the shape of a valve head; and then cooling the head in two stages, during the first of which the head is cooled to a point below the point of recalescence by applying a cooling medium to the main portion of the stem and during the second of which the final'cooling is effected by quenching the head.

2. The method of making a two-part valve which consists in inserting a stem into a hole of larger diameter extending through a heated valve-head blank; then forging the blank, in dies, while supporting the stem so that it may expand lengthwise, in either direction, to cause the metal to flow into intimate contact with the stem; and then cooling the head in two stages, during the firstof which the head is cooled to a point below the point of recalescence, by applying a cooling medium to the main portion of the stem and during the second of which the final1 cooling is effected by quenching. the

In testimony whereof I sign this specification.

- WILLIAM H. WASHBURNE. 

